This invention relates to orthoses for providing assistance in walking. Such orthoses may assist persons having any of several types of walking disability, but they have particular utility for persons who have been paralyzed by a spinal cord injury. Such persons may in some cases attain walking movement by use of an appropriate orthosis. In other cases the orthosis may be used in combination with functional electrical stimulation to produce stimulated walking as described in Larson et al., U.S. Pat. No. 4,697,808.
Background information on stimulated walking is contained in Petrofsky et al. U.S. Pat. No. 4,569,352 and in a technical article entitled "Feedback Control System For Walking In Man" Petrofsky et al., COMPUT. BIOL. MED., 14:135-139, 1984. Apparatus as described in those references may use stimulation devices of the general type disclosed in Petrofsky et al. U.S. Pat. No. 4,492,233 for stimulating muscular contractions in the lower body of the person being assisted by the system. Reference may also be made to Petrofsky U.S. Pat. No. 4,711,242 which discloses a control system for a knee joint incorporated within an orthosis of the general type described in Larson et al and to Phillips et al. U.S. Pat. No. 4,760,850 for a method of assisting the balance of a person who is being stimulated to walk.
The preferred orthosis heretofore available for use in stimulated walking has been that shown in Larson et al. That orthosis enabled considerable simplification of the stimulation system. However, the orthosis uses rigid bracing which inhibits desired body flexing. That results in a relatively jerky walking gait which causes premature fatigue of critical components of the orthosis. It also tires the user. Furthermore, it has been found that walking is difficult for a person using that orthosis on an incline, particularly uphill. This is due in part to the fact that the upper body is constrained in a rigid vertical orientation. When a normal, non-handicapped person walks up or down a hill, he leans his body forwardly or backwardly depending upon the grade. The Larson et al. orthosis will not permit such a grade adjustment.